Beamsplitters available in the prior art use a large plate that is a fragile and expensive component since it is used near grazing incidence. The size of the beamsplitter is dictated by the large value of Brewster's angle resulting from the use of the external surface, the lower to higher dielectric constant interface, for splitting the linearly polarized components. This means that any auxiliary beam-splitting, as in heterodyned laser radar systems for example, must be mounted at some distance and the set of beam-splitters must be held in stable alignment. Another problem found in beamsplitters is the interference that can take place between multiple bounces inside the plate. This can lead to a variation in throughput by over a factor of two.
Additionally, a conventional beamsplitter used in a laser system does not prevent some of the reflected signals from leaking into the laser tube, thus perturbing the frequency of oscillation.